add both v2 and v3 tests for get specified extension

this add tests for getting specified extension info both against
on nova v2 and v3 api.

Partially implements blueprint nova-v3-api-tests

Change-Id: I9e254069db737d3eb9088475d7272d8aa79b1bd1
Remove duplicate negative test of flavor_id

As tempest/api/compute/admin/test_flavors.py, it is possible to
specify uuid as flavor_id. In addition, Nova creates a flavor with
uuid flavor_id if passing None as the API parameter of flavor_id.

Then, test_get_flavor_details_for_invalid_flavor_id is not an
"invalid id" test, the test is a "non existent id" test.
So the test and test_non_existent_flavor_id are duplicated, and
this patch merges them to one test.

Change-Id: I73f79f82f48a49208500c2542e55c026f120e921
Move common wait_for_image_status from compute images_client to waiters

The wait_for_image_status method in the compute json/xml images_clients
was copy/paste and needed a better error message when it times out, so
rather than write a better error message and copy it in both places,
move the common code into waiters and make the json/xml clients call
that instead, like we do for wait_for_server_status.

The improved error message should help in debugging that failure when
it's hit.

Related-Bug: #1260982

Change-Id: I5e3e33310a91da71467fa744972f1a0e4c0bdb50
Separate negative tests for test_availability_zone

Move negative tests from test_availability_zone.py to
test_availability_zone_negative.py

This patch also uses 'AZ' short for the 'AvailabilityZone'.
This is because if the class name 'AvailabilityZoneAdminV3
NegativeTestJSON' is used, the tempest test will occur an
error 'Project name should not be greater than 64 characters.'
The Project name is made of class name and the characters
'-tempest-xxxxxxxxxx-tenant'.
'-tempest-xxxxxxxxxx-tenant' is 26 characters, so the class
name should not exceed 38 characters.

Partially implements blueprint negative-test-files
Change-Id: Ic72264e89ac5fd700202b0c75cc63116d8fca172
Fix three accidentally formatted paragraphs

Three paragraphs are misformated in the output due to
a leading space in a line. The leading space causes a
line break and the indent of the line.

Change-Id: I5c0d03a47a2ca305b2b077068df26fadccd72212
Merge "Fix three accidentally formatted paragraphs"
Merge "Separate negative tests for test_availability_zone"
Merge "Remove duplicate negative test of flavor_id"
Merge "Move common wait_for_image_status from compute images_client to waiters"
Merge "add both v2 and v3 tests for get specified extension"